As the demand for data traffic increases with the rise of a connected society, rural broadband service providers (BSPs) are under pressure to improve their backbone network performance.
To address this, 400ZR technology has been developed to offer flexible hardware configurations and enable 400G speeds. Although initially designed for enterprise data centre interconnection, 400ZR has now been expanded to include multiple versions suitable for BSPs of all sizes. By selecting the appropriate 400ZR standard equipment, rural BSPs can benefit from improved capacity and cost efficiency.
OpenZR+
OpenZR+ is considered the most appealing 400ZR standard for regional networks due to its unique features. Initially, the 400ZR project focused on 400G Ethernet, utilising amplified point-to-point DWDM links for data centre interconnectivity up to 120 kilometres.
Additionally, unamplified single-wavelength links with a loss budget of 11dB were also supported. However, the 400ZR+ standard was later introduced to cater to the communication service provider’s requirements, extending the range beyond 120 km and enabling a 4x 100G client rate, in contrast to only 1x 400G.
OpenZR+ was created by combining the best aspects of 400ZR+ and Open ROADM standards, with the aim of providing simplified functionality, high-performance oFEC, and interoperability tailored to the needs of regional networks. It provides more flexibility to the line rate and line modulation, along with interoperability that was absent in 400ZR+. Eventually, OpenZR+ will replace 400ZR+.
When referring to 400ZR broadly, it encompasses all three standards as a whole. Specifically, the original 400ZR standard by OIF is referred to as OIF400ZR to distinguish it from 400ZR+ and OpenZR+.
The table outlines the varying targets of the standards and how they have influenced the supported distances and rates.
| Name | OIF400ZR | 400ZR+ | OpenZR+ |
| Target application | Edge DCI | Vendor dependent | Regional networks |
|
MSA |
Yes |
No |
Yes |
|
Mid span |
Yes | No | Yes |
|
Distance |
80-120km |
≥ 120km |
≥ 120km |
| Client rate | 400GE | 400GE / 4x 100GE | 100GE/200GE/400GE |
| Line rate | 400G | 400G | 100G/200G/300G/400G |
| Line modulation | DP-16QAM | DP-16QAM | DP-QPSK/DP-8QAM/DP-16QAM |
| FEC | CFEC |
CFEC/oFEC/prop FEC |
oFEC |
| Form factor | QSFP-DD/OSFP/CFP2 | QSFP-DD/OSFP/CFP2 | QSFP-DD/OSFP/CFP2 |
Increased Flexibility In Regional Networks
By adopting 400ZR technology, the level of standardisation surpasses that of previous standards, which drives the trend of disaggregated solutions. Consequently, it becomes simpler to integrate various network building blocks from different vendors, resulting in more cost-effective and less complicated high-speed networking solutions.
The use of 400ZR technology facilitates the creation of solutions with improved interoperability, ranging from transceivers and open line systems to open ROADMs and management solutions. Rural CSPs can take advantage of this by reducing vendor lock-in, increasing flexibility and deploying solutions that are future-proof.
Building Future-proofed regional networks
There are two types of pluggable form factors of 400ZR transceivers that are most useful for rural BSPs: QSFP-DD and OSFP. The convenience of pluggable form factors makes them effortless to deploy and manage in regional networks.
QSFP-DD has double the number of high-speed electrical interfaces compared to its predecessors (QSFP+, QSFP28, QSFP56) while maintaining the same convenient form factor. This results in an increase in aggregate bandwidth from 40G or 100G to 200G or 400G, respectively, enabling a total bandwidth of 14.4T for a single switch.
OSFP, on the other hand, is a larger form factor than QSFP-DD and supports higher power consumption. It also supports 400ZR with the same aggregate bandwidth per switch of 14.4T and 400G speeds but has the potential to support up to 800G in the future.
While OSFP may be more future-proof, QSFP-DD transceivers have been more popular with rural BSPs so far. This is because they are backward compatible with previous QSFP system transceiver modules, making upgrades a streamlined process. Therefore, QSFP-DD transceivers can be easily connected to existing switches and other infrastructure without requiring the replacement of everything.
The 400ZR is a standardized format that perfectly aligns with our open philosophy and is highly suitable for use with open-line systems. This technology plays a pivotal role in achieving greater cost efficiency and flexibility, allowing you to choose the most suitable network elements with the best value for money. Integrating our open line systems with pluggable 400ZR transceivers will simplify your 400ZR upgrade process and ensure the longevity of your network. You can enjoy cost-effectively, automated 100G networking and also gain support for 400G, future-proofing your network.
